New tank holes too large for bulkheads - fixes?

Discussion in 'Tank Talk' started by djkaty, Aug 11, 2010.

  1. djkaty

    djkaty Vampyroteuthis Registered

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    So I had a 180 L tank with two 45mm (1.75in) holes for the overflow box outtakes.

    I upgraded to a 343 L tank and the person who cut the holes made them 51mm (2in) despite me giving him the overflow box to use as a measurement.

    I have two bulkheads from the old tank, 32mm (approx 1 1/4in) inside diameter, 40mm (approx 1 1/2in) outside diameter plus rubber gaskets, measurements below.

    What is the best way of getting this stuff to fit together now?

    Pictures of the fittings:

    http://www.facebook.com/photo.php?pi...&ref=fbx_album

    http://www.facebook.com/photo.php?pi...&ref=fbx_album

    Approximate measurements are (diameter):

    Tank holes - 51mm
    Overflow box holes - 45mm
    Pipes outside diameter - 40mm
    Pipes inside diameter - 32mm
    Small gasket inside: 40mm
    Small gasket outside: ~54mm
    Large gasket inside: 40mm
    Large gasket outside: ~60mm

    Silicone? Replacement gaskets? Replacement bulkheads? If so, what sizes - I am useless at this kind of thing :/

    Thanks!

    Katy.
     
  2. CaptFish

    CaptFish Colossal Squid Staff Member Moderator

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    I would drill the overflow box to match the holes on the tank and get new bulkheads that fit.
     
  3. djkaty

    djkaty Vampyroteuthis Registered

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    That would be great if I knew how to drill acrylic/plastic or had the tools to do it... :S
     
  4. CaptFish

    CaptFish Colossal Squid Staff Member Moderator

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    Hmmm, drilling acrylic is very easy, but does require the proper tools. You could buy the drill bit,they are fairly cheap, then you just need a friend with drill.
     
  5. djkaty

    djkaty Vampyroteuthis Registered

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    Yeah they linked to the hole saw piece I would need on reefcentral. I have a drill but I will get Thomas to do it :P But, before I do that.. I was just told by one of my colleagues that there is a plumbing place not far from here (10 minute walk), so I will take the problem box and bulkheads down there tomorrow and see if they can just fix it and provide the right pieces for me.

    Assuming for a moment though that they can't, this still leaves the problem that the standard sizes are 32mm and 40mm and require holes of 45mm and 55mm and that my tank has 51mm holes in it. I have found those standard sized items easily on Norwegian aquarium shops online but to find one that can use a 50 or 51mm hole seems impossible.

    Someone on reefcentral also linked to this:

    http://www.aquacave.com/1-bulkheads-sch-80-1270.html

    A 1in bulkhead that requires a 1 7/8in hole. I don't know if that would work, or where to get one here; and if I get a larger bulkhead, won't the pipes I have be too small to fit on it?

    Webzoo also has a range of imperial-to-metric and vice versa convertors:

    http://www.webzoo.net/default.pl?showPage=832

    but with no pictures I don't know what would work. They also have 'bushings':

    http://www.webzoo.net/default.pl?showPage=835

    All of which left me quite confsued. I hate plumbing lol.
     
  6. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Neal and I sat down and thought about the situation. Looking at standard bulk heads, redrilling the overflow is likely to cause more problems rather than fixing anything. The tank hole is too small for a 2" and too big for a 1" bulk head. When I asked him how he sealed our overflows to the tube tank, he confirmed my original thinking that he had used heavy silicone around the holes as well as along the back and then clamped the overflow to the tank wall to let it dry (the bulk heads will work as a clamp). He also brought up an important issue about how the bulkhead would seat at the back of the tank since the hole is too large and suggested adding an acrylic plate drilled to the original overflow box hole size (the size of the threaded part of the bulk head). I made an attempt at an exploded sketch (I am neither CAD nor graphics literate so excuse the esthetics).

    I am concerned about you using the existing DIY bulkheads and even wonder if the way they were used allowed the original tank to crack more easily because the required over tightening. If the standard 1" bulk heads fit the overflow opening, they would be much better to use than the make shift parts you have. Neal asked me to be sure and mention that this kind of fitting should be hand tightened and then use a wrench for only about 1/4 of a turn.
     

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  7. djkaty

    djkaty Vampyroteuthis Registered

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    Dang D, that would've taken me two days to draw. Thanks very much to the both of you for coming up with that. The bulkhead sizes here appear to be different in standards, 32mm (requiring 45-46mm hole) or 40mm (55-56mm hole) but the principle is the same. The bulkheads I have aren't DIY, afaik they are a standard size, 32mm, seen identical parts online in Norwegian aquarium stores.

    Anyway, I called the plumber that my colleague told me about and explained the problem, got an appointment on Monday morning... at 7am *rolls eyes and groans*... so hopefully they will fix it, or give me the parts at least.

    Regarding tightness, I tend to agree. What happened when I carried the original aquarium up my spiral staircase is that I tripped and the pipe (which was still attached) hit the banister and cracked the tank outwards from the pipe hole in several places. I had to do 1-2 turns per bulkhead with the rørtang (tool) to be able to loosen the rest with my hands.
     
  8. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    One of Neal's major concerns is that you have a nut (the ring that screws on the back) that will seat wholly against the glass. The suggested fix is marked in green. The drawing has no scale but I think it does better than trying to explain without it :oops:.

    I have the occassion to have to create a few graphics for websites so I have a half decent piece of UK software that lets me make passable representations most of the time. For fun, I have created a few of our icons and always have to grin when someone uses one.
     
  9. djkaty

    djkaty Vampyroteuthis Registered

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    It doesn't sit flush against the glass though - isn't that what the white plastic rings I have are for?
     
  10. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Humm, WHAT part does not fit flush against the glass? There is a difference in what you have and what we use here so I need a better understanding.
     
  11. djkaty

    djkaty Vampyroteuthis Registered

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    Ok, let's take it from the top because in the last few days I've learned enough about plumbing to be able to explain it properly:

    The overflow box has two outtakes with 45mm holes. So did the old tank. The new tank has two outtakes with 51mm (exactly 2in) holes.

    The standards here are a 32mm bulkhead which requires 45mm holes, or a 40mm bulkhead which requires 56mm holes.

    The bulkheads I have are threaded on the inside tank (base) side, and slip on the outside tank (flange I believe) side.

    Each bulkhead has two rubber gaskets, one slightly larger than the other, and one white ring of plastic (like a washer but larger and plastic) the same size as the larger gasket. Unfortunately I've now become confused what order the gaskets and ring go in despite disassembling it carefully (I thought) :/

    But as said there are two gaskets and one plastic ring per bulkhead; my recollection is that one of them went outside the tank between the glass and the thickest part of the bulkhead; another piece goes between the inside glass of the tank and the outside wall of the overflow box, and the third piece goes between the inside wall of the overflow box and the part of the bulkhead you turn to tighten.

    Does that provide any clarification? :/
     
  12. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Well, now I can't get to your original pictures either. I need to look again because it is odd to tighten from the inside (normally the nut would be on the outside). Check your facebook share but I was able to see the links earlier.
     
  13. djkaty

    djkaty Vampyroteuthis Registered

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  14. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Yes, I can see the full album from that link. I went back an looked at your Day 4 video to see how the bulkheads were set up. They are backwards from the way the ones we use here are designed to be installed and I suspect that is also the design intent of the one you have.

    The idea is to get a water tight seal on the inside and the rubber gasket between the bulkhead and the inside wall provides the water proofing once it is tighly fastened. The reason for rubber or a rubberized material is to allow it to compress slightly and conform to any tiny irregularities in the plastic of the bulkhead or wall (water can get through even tiny, tiny holes) and that is why you should always replace the gaskets once your remove the bulkhead.

    You have complications because you are going through two, detached walls (the overflow box and the tank wall). The suggestion to silicone the box to the tank is to get a water tight seal between the box and the tank so that the bulkhead is only working to seal a single wall. It appears that the original overflow box may have used a rubber gasket between the overflow box and the tank wall to prevent a leaks but with the oversized outside hole, you may need to rethink how to create this seal.

    The outside of the tank is not a sealing point in the configuration but the wall is used to seat the rubber gaskets on the inside through pressure. Unless the bulkheads are very different, both the inside and the outside contact points should be flush to a flat surface (and is why Neal suggested the need for an acrylic panel drilled to the correct hole size place over the back hole so that there is a flat surface to provide tension. You might Google european aquarium bulkhead installation to see if you can identify an oddity in this style bulk head as I have no understanding of how he used the nylon (white) washer.
     
  15. djkaty

    djkaty Vampyroteuthis Registered

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    Ok, that made everything crystal clear, I see and understand the concepts and your plan for the fix now, thank you very much.

    I had done some Googling on the subject over the last days and just got confused with the English terminology. I found a product page with identical bulkheads to these, and I know the previous owner also shopped at this site:

    http://www.webzoo.net/default.pl?showProduct=5332&pageId=823

    As you can see they have the nylon washers, although only one rubber gasket, so he has added the 2nd ones. From your description, and my own thoughts that it was weird the thread was on the inside of the tank where I would've expected a smooth grooveless pipe at least aesthetically, it seems highly likely it was installed backwards.

    Taking just the rubber gasket shown in the product picture above, the inside diameter is 41mm and the outside diameter is 60mm, so that ought to be able to make a seal (4.5mm clearance in all directions on a 51mm hole), right? (notwithstanding what you said about replacing the gaskets after use). In that case, the problem could just be that I re-assembled it with the gaskets in the wrong place...
     
  16. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    I suspect the second, nonstandard rubber gasket was used between the box and the tank wall as that has to be sealed separately and would make sense, what I don't understand is the nylon washer so keep looking to see what purpose it provides (it is not for sealing and not something we use here.)
     
  17. djkaty

    djkaty Vampyroteuthis Registered

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    Aha, found something interesting after much searching:

    http://www.fishforums.net/index.php?/topic/330129-bulkhead-keep-the-rubber-seal/

    This gentleman has exactly the same bulkheads as me and asks where to place the rubber and plastic washers. The respondent shows pictures of how he assembled his. Although my eyes are not good enough from the pictures to see whether he put the thread on the inside or outside. Take a look at that page.
     
  18. rryyddeerr

    rryyddeerr Vampyroteuthis Registered

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    you want the nut to tighten on the outside. much easier to service later on. ive tried it both ways. what you may consider is trimming off the unneeded threads with a saw once you figure out exactly how much of them you need.
    bulkheads look much cleaner and nicer with the nut on the inside, but its, functionally, not as useful.
     
  19. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    rryyddeerr,
    The bulkhead she has has a nylon washer as part of the setup. I have no idea how that is supposed to be used. Look at her photos. There are two rubber gaskets (the second was probably used to seal between the overflow box and the tank wall, I still vote silicone there instead) but I can't fathom the intent of the nylon washer (our bulkheads do not use these). The thread she found suggesed siliconing everything but seating a gasket would still be my choice where the bulkhead hits the overflow.

    Katy, is there an inside groove in either side of the bulkhead where the nylon would fit and be resessed? It's use is a mystery.
     
  20. djkaty

    djkaty Vampyroteuthis Registered

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    Just checked. There are no grooves like that, no. My only thought about that washer is that it is meant to be used between the nut and the glass to protect the glass or reduce the likelihood of cracking, like your acrylic plate solution. Other than that, I'm blank.
     

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